During the molding and subsequent handling of large plastic articles, such as automotive body panels, various minor surface defects such as porosity, scratches, gouges and sand-throughs can be formed due to minor departures from optimum operating conditions or procedures. Sand-throughs can occur by sanding through the smooth exterior surface of the molded body panel when attempting to effect cosmetic repairs such as removal of adhesives or bumps. Such defects can arise, for example from dirt or debris inadvertently entering the mold before or with the mold charge, or from a variety of other reasons. Also, small dents, scratches or other surface blemishes can also arise while removing the article from the mold or during subsequent handling. Often such minor defects or blemishes do not adversely affect the structural or functional characteristics of the molded article but impart an unacceptable appearance which cannot be effectively corrected with normal finishing operations such as painting.
Because large molded articles formed from thermosetting SMC and BMC are relatively expensive to produce, a method for quickly, easily and inexpensively repairing minor defects which mar the appearance of otherwise usable molded articles would be highly desirable.
U.S. Pat. No. 4,409,270 to Faber et al. discloses a method for repairing a surface defect in a thermoset fiberglass reinforced polyester or vinyl ester resin. In accordance with the teachings of Faber et al., an excess amount of a thermosetting repair material is used to fill a defect in the surface of a thermoset substrate. Sufficient amounts of heat and pressure are applied to the repair material for a time sufficient to cure the repair material. After curing, the part is allowed to cool and then the part is finished by removing excess repair material to return the part to its original contour. The method is relatively time consuming and cumbersome requiring the application of a liquid repair material and the simultaneous application of heat and pressure for periods of time up to about 20 minutes.
U.S. Pat. No. 5,021,297 to Rhue et al. discloses a method of coating a fiber reinforced plastic substrate with a powder coating composition to seal the substrate against gassing. The teachings of Rhue et al. relates to a routine procedure which is used to remedy appearance problems associated with the eruption of volatile materials during the cure which cause pores in the surface. The teachings of Rhue et al., however, do not relate to, nor do they suggest, a method by which spot repairs can be made as required to correct for scratches gouges, sand-through and other defects.